1. Field of the Invention
The present invention relates to a rotor and, more particularly, to an engine core structure for use in the gas turbine engine of a centriflugal type compressor.
2. Description of Related Art
FIG. 1 illustrates a conventional gas turbine engine 9 formed of a compression section 91, a combustion section 92, and a turbine section 93. The gas turbine engine 9 comprises a casing 94, an engine core rotor 95 installed in the casing 94, and an annular combustor 96 mounted in the annular space defined within the casing 94 around the core shaft 950 of the engine core rotor 95. The intake air is compressed and delivered (compressor rotor 941 and stator 951) to the combustor 96 at substantially increased pressure and temperature. There, the fuel is burned and the temperature raised to a higher value. Then, the hot, pressurized combustion gases expand through a series of rotating turbine wheel and blade assemblies (high pressure turbine 952, power turbine 971) resulting in shaft power output, propulsive thrust, or a combination of the two.
The diameter of the core shaft 950 is limited in the configuration of a conventional gas turbine. Due to limited diameter, it is difficult to improve the rigidity of the core shaft 950 and its vibrations. Vibration due to resonance is a serious problem which is more apparent in a high-speed micro gas turbine engine.
Further, because the annular combustor 96 is installed in the annular space within the casing 94 around the core shaft 950, the space occupation of the annular combustor 96 does not meet the requirement for compact design. Furthermore, the arrangement of the annular combustor 96 around the core shaft 950 may cause heat dissipation.
Therefore, it is desirable to provide an engine core rotor for gas turbine engine that eliminates the aforesaid drawbacks.
It is the main object of the present invention to provide an engine core structure for a gas turbine engine, which greatly enlarges the diameter of the shaft to increase its rigidity and avoid vibration due to resonance of the shaft, so as to further improve the stability and service life of the engine core. It is another object of the present invention to provide an engine core structure for a gas turbine engine, which keeps the combustor arranged inside the shaft to meet compact design requirements, so as to reduce heat dissipation and improve the thermal efficiency of the gas turbine engine.
To achieve these and other objects of the present invention, the engine core rotor shaft structure for a gas turbine engine comprises an outer annular shaft body, a gas turbine rotor body and high-pressure turbine (HPT) rotor blades. The outer annular shaft body is a hollow annular shape that extends in an axial direction and that comprises a front section, a rear section, and a middle section connected between the front section and the rear section and defining a receiving chamber. The outer diameter of the gas turbine rotor body is smaller than the inner diameter of the rear section of the outer annular shaft body. The HPT rotor blades are radially extended outwardly from the gas turbine rotor body and fixedly connected to the rear section of the outer annular shaft body. The gas turbine rotor body is coaxially provided in the rear section of the outer annular shaft body. Because the diameter of the outer annular shaft body is greatly increased, the rigidity of the shaft of the gas engine rotor is improved, and the critical speed of the shaft is increased, and therefore the stability of the rotation of the shaft is improved and the service life of the shaft is prolonged. A can type combustor is mounted in a receiving chamber inside the outer annular shaft body to save space, to eliminate dissipation of heat, and to improve the thermal efficiency of the gas turbine engine. A front annular shaft body of relatively smaller diameter may be provided inside the front section of the outer annular shaft body. High-pressure compressor (HPC) rotor blades are radially extended outwardly from the periphery of the front annular shaft body and fixedly connected to tie front section of the outer annular shaft body. The front annular shaft body is coaxially mounted inside the front section of tile outer annular shaft body.